Method and apparatus for handling cryogenic liquids



- Jan. 3, 1967 LAYA ETAL METHOD AND APPARATUS FOR HANDLING CRYOGENICLIQUIDS Filed Dec. 27, 1963 fzz v5.27 furs lam refine 159/3 5 Job @420 JUnited States Patent C) METHOD AND APPARATUS FOR HANDLING CRYOGENICLIQUIDS Lawrence Laya, Chicago, Ill., and John Cupp, Lexington, Mass.,assignors to General Dynamics Corporation, New York, N.Y., a corporationof Delaware Filed Dec. 27, 1963, Ser. No. 333,859 6 Claims. (Cl. 141-1)The invention relates to the handling of cryogenic liquids and moreparticularly to filling small containers with cryogenic liquids fromlarger supply reservoirs.

When one fills a relatively small container with a cryogenic liquid,such as liquid oxygen, liquid argon or liquid nitrogen, from apressurized supply container, it is important that he use extremecaution lest the cryogenic liquid splash. The danger of careless orinadvertent splashing of a fluid having the freezing power of a liquidat a temperature of about 160 C. is obvious. Furthermore, because it isnot usually economical to attempt to recover vapors given off when acryogenic liquid of this type evaporates, it is also important thatevaporation be minimized to reduce loss of the cryogenic fluid and keepthe cost of using such a fluid as low as possible.

It is an object of the present invention to provide an improved methodfor handling cryogenic liquids and apparatus for carrying out such amethod. It is another object to provide an improved method for fillingcontainers from pressurized supply reservoirs of cryogenic liquids andapparatus for carrying out such a method. It is a further object of thepresent invention to provide improved apparatus for filling containerswith cryogenic liquids which is simple in construction and operation andinexpensive to manufacture.

These and other objects of the invention are more particularly set forthin the following detailed description and in the accompanying drawingswherein:

FIGURE 1 is a perspective view of apparatus embodying various featuresof the invention shown being used in filling a small container from alarge pressurized cylinder of a cryogenic liquid;

FIGURE 2 is an enlarged sectional view of a portion of the apparatusshown in FIGURE 1 taken along line 22 of FIGURE 1; and

FIGURE 3 is an enlarged view, partially in section of another portion ofthe apparatus shown in FIGURE 1.

Generally, the invention comprises throttling the flow of a stream ofcryogenic liquid which is under superatmospheric pressure in order todischarge cryogenic liquid to the atmosphere in a manner so thatsplashing and evaporation of the cryogenic liquid is minimized. In theapparatus contemplated, a throttling device including a porousthrottling element is interposed in the flow of cryogenic liquid so thatthe liquid must pass through the throttling element to be discharged tothe atmosphere.

As illustrated in FIGURE 1, cryogenic handling apparatus 5 is providedwhich is adapted to regulate the flow of a cryogenic liquid so thatsmall containers, such as a Dewar flask 7, can be safely filled from alarge, pressurized cylinder 9 of cryogenic liquid. Basically, theapparatus 5 includes a tubular conduit 11 and a throttling device 13attached to one end of the conduit 11. The other end of the conduit 11carries a connector 14 for connection with an outlet 15 on the supplycylinder 9.

The conduit 11 is constructed in the illustrated embodiment with a 90bend, so the discharge from the throttling device 13 is downward. Afterthe connector 14 is secured to the cylinder outlet 15, a valve at thetop of the pressurized cylinder 9 is opened by a small handwheel 17 toallow cryogenic liquid to flow into the apparatus 5. A gauge 19, whichis incorporated in the cylinder 9, indicates the pressure in thecylinder and allows regu- 3,295,563 Patented Jan. 3, 1967 lation of thevalve handwheel 17 so that the pressure at which the handling apparatus5 is operated is within desirable limtis. Cryogenic liquid flowsdownward from the bottom of the throttling device 13 in a tranquilstream, the velocity of which is little above that which results fromthe force of gravity. This stream can easily be caught in the open-mouthDewar flask 7 without danger of splashing.

The conduit 11 may be of any material that is suitable for use withcryogenic fluids, such as copper tubing. As best seen in FIGURE 3, theconnector 14 at the upper end of the conduit 11 is of standard designand includes a central stem 25 which is brazed to the end of the conduit11. A rotatable nut 26 rides on the stem 25 and contains internalthreads which are matched to the threads on the outlet 15 of a standardpressurized cylinder. By tightening the nut 26, the stem 25 is forcedtogether with the internal bore in the outlet 15 creating a tight seal.

The opposite or lower end of the conduit 11 has a bushing 27 made of amaterial such as a brass brazed to it. The bushing 27 has a smoothinternal bore and external threads by which the throttling device 13 isattached.

The throttling device 13 includes a porous throttling element 29 in theform of a hollow thin-walled cylinder, closed at its bottom, somewhatsimilar in shape to an ordinary drinking glass. The throttling element29 is secured at its top to the bottom of an adapter 31, generallycylindrical in shape, which has a lower circular seat 32 against whichthe throttling element is positioned. A central bore 33 extends throughthe adapter 31; the bore 33 is threaded internally from the top.

A generally bell-shaped sheath 34, having an open bottom and fairly flattop, laterally surrounds the throttling element 29 and is of suflicientlength to extend below the bottom of the element 29. The sheath 34 isattached to the cylindrical adapter 31 by a bushing 35 which extendsthrough an aperture in the top of the sheath 34. External threads on thebushing are matched to the internal threads in the bore 33 of theadapter 31. A pair of washers 37 are disposed on each side of the top ofthe sheath 33. The internal threads on the bushing 35 are matched to theexternal threads on the bushing 27, attached to the bottom of theconduit 11, and afford connection of the throttling device 13 to theconduit. Because the throttling device 13 is used with cryogenic fluids,Teflon tape is preferably used between the two bushings and between thebushing 35 and the adapter 31 to assure a tight seal at the threadedjoints.

In the operation, the cryogenic fluid enters the internal cavity of theelement 29 at the desired pressure and is herein throttled. The porosityof the element 29 is preselected so that, when the fluid enters theatmosphere outside the element 29, the force driving the fluid as aresult of the pressure differential between the pressurized cylinder andthe atmosphere has been substantially dissipated in forcing the fluidthrough the interstices of the porous element 29. Accordingly, thevelocity of the cryogenic fluid is relatively low. Moreover,-by passagethrough the porous element 29 the flow of cryogenic fluid from thecylinder 9 has been split from one main stream into an extremely largenumber of minute or extremely fine streams. The number of streamsprovided by the sintered throttling element 29 is at least manyhundreds. It has been found that these minute streams of low velocityhave a far less tendency to splash than a larger stream or streams.

The porosity of the throttling element 29 is pre-selected to split thesingular stream of cryogenic liquid into a suitable number of minutestreams and to reduce the force of the liquid to a level where splashingis inhibited when cryogenic liquid is fed into the handling apparatus 5within a desired pressure range. It has been found that a throttlingelement 29 made from a sintered metal is especially well adapted tocarry out these functions. Accordingly, sintered metal is the preferredmaterial, although other suitable materials such as porous cloths orplastics might be used. Examples of suitable metals include, but are notlimited to, bronze, brass and stainless steel.

For pressures in the range of about 25 p.s.i.g. to 75 p.s.i.g., it hasbeen found that sintered bronze element having a wall thickness of aboutone-eighth inch and having pores about 25 microns to about 40 microns indiameter is considered suitable. For higher and lower pressures,elements 29 having pores with lower and higher average pore diameters,respectively, are suitable, preferably in the range from about 5 micronsto 50 microns. The wall thickness may also be altered.

A further advantage of the thin-walled sintered metal element is that ithas a low mass and is thus quickly cooled to the temperature of thecryogenic liquid. Thus, evaporatoin of cryogenic liquid in order to coolthe element to operating temperature is held to a minimum.

The design of the throttling element 29 provides a large surface area ina relatively small space. The entire lateral surface and the bottom faceof the element 29 provide throttling passageways, in which the flow ofcryogenic liquid is broken into minute streams. In order to safelyutilize the element 29 with tanks or cylinders at pressures above about50 p.s.i.g., the sheath 34 is disposed in surrounding relation to thethrottling element 29 to divert laterally directed streams, which mayoccur when working at such pressures, downward, out the open bottom andinto the intended container.

The sheath 34 may be made of any material which is suitable for use withcryogenic liquids. Preferably, the sheath is made of a transparentmaterial, such as clear polyethlene, so that the exit flow from thethrottling element 29 can be observed, to further aid in keeping thepressure released to the throttling device 13 within the desired range.However, liquid nitrogen, liquid argon and liquid oxygen are among thecryogenic liquids with which the handling apparatus 5 is especiallyadapted to be used. Because of the ever present danger of combustionwhen pure oxygen is present, a sheath 34 made from a non-combustiblematerial, suchas stainless steel, may be preferred.

The sheath 34 has a large opening at the bottom and is designed for usein filling open-mouthed Dewar flasks. If the apparatus 5 is to be usedto fill closed-mouth Dewar flasks, the sheath 34 can be made, intwo-pieces, so that it narrows at its bottom in funnel-like fashion.

It is contemplated that the throttling device 13 will be used withconduits having different types of connectors adapted to fit differenttypes of supply tanks. The throttling device 13 may also be used withflexible high pressure tubing instead of the. generally rigid conduitillustrated.

Various features of the invention are set forth in the following claims.

What is claimed is:

1. Apparatus for filling containers with cryogenic liquids from largertanks under superatmospheric pressure which apparatus comprises athrottling element made of a porous sintered metal, means attached tosaid throttling element for connecting said element to conduit meansfrom a tank of cryogenic liquid so that cryogenic liquid from said tankis afforded a path to said throttling element and into a container atatmospheric pressure through said throttling element, said poroussintered metal throttling element having the shape of an uprightcylinder closed at the bottom with its open top end in fluidcommunication with said conduit means, and sheath means laterallysurrounding said porous throttling element for diverting lateral flow ofcryogenic liquid from said element downward into an intended container.

2. Apparatus 'for filling containers wit-h cryogenic.

liquids which comprises conduit means for passage of liquified gas,means for attaching one end of said conduit means to a supply ofcryogenic liquid, a throttling element made of a porous material, meansattaching said throttling element to the other end of said conduit meansso that liquid which passes through said conduit means exits to acontainer through said throttling element, said porous throttlingelement having the shape of an upright cylinder closed at the bottomwith its open top end in fluid communication with said conduit means,and sheath means laterally surrounding said porous throttling elementfor diverting lateral flow of cryogenic liquid from said elementdownward into an intended container.

3. Apparatus for filling containers with cryogenic.

liquids from a tank under superatmospheric pressure, which apparatuscomprises a throttling element made of porous sintered metal, meansattached to said throttling element for connecting said element to atank of cryogenic liquid so that cryogenicliquid from said tank isafforded a path to said throttling element, said throttling elementhaving a pre-selected porosity that reduces the force of said liquid toa level where splashing of the cryogenic liquid after passagetherethrough is minimized, and shield means partially surrounding saidthrottling means and open to the atmosphere at one location to permitescape of vapor generated therethrough and to direct the cryogenicliquid passing through said throttling element into a container atatmospheric pressure.

4. Apparatus for filling containers with cryogenic.

liquids from a tank under superatmospheric pressure,

which apparatus comprises a throttling element made of a porous sinteredmetal, means attached to said throttling element for connecting saidelement to a tank of cryogenic.

liquid so that cryogenic liquid from said tank is afforded a path tosaid throttling element, said throttling element having a pre-selectedporosity that reduces the force of said liquid to a level wheresplashing of the cryogenic liquid after passage therethrough isminimized, and shield means partially surrounding said throttling meansand open to the atmosphere at one location to permit escape of vaporgenerated therethrough and to directthe cryogenic liquid passing throughsaid throttling element into a container at atmospheric pressure, saidconnecting means,

'to a filling means, throttling said cryogenic liquid at said fillingmeans and splitting said fiow into a multitude of small streams, anddirecting the flow of said multitude of small liquid streams into acontainer at atmospheric pressure to fill the container with minimalsplashing of said liquid.

6. A method of filling a container with cryogenic liquid,

which method com-prises establishing a flow of cryogenic liquid from asource thereof under superatmospheric pressure, conducting said flow ofcryogenic liquid to a. filling means, throttling said cryogenic liquidat said. filling means by passing it through a porous body having anaverage pore diameter of about 25 microns and thereby splitting saidflow into a multitude of small streams,

shielding the flow of said multitude of streams in other directions todirect all of said streams generally down- J Ward, and filling acontainer at atmospheric pressure with FOREIGN PATENTS Said. liquidWit-h minimal splashing Of said liquid. 13 05 1906 Great Britain-References Cited by the Ex er 501,863 3/1939 Great Bntaln.

UNITED STATES PATENTS 5 SAMUEL ROTHBERG, Primary Examiner.

1,947,586 2/1934 Flfictchel 13 LAVERNE D. GEIGER, H. S. BELL,

2,576,610 11/1951 Kunzog 13841 Assistant Examiners.

5. A METHOD OF FILLING A CONTAINER WITH CRYOGENIC LIQUID, WHICH METHODCOMPRISES ESTABLISHING A FLOW OF CRYOGENIC LIQUID FROM A SOURCE THEREOFUNDER SUPERATMOSPHERIC PRESSURE, CONDUCTING SAID FLOW OF CRYOGENICLIQUID TO A FILLING MEANS, THROTTLING SAID CRYOGENIC LIQUID AT SAIDFILLING MEANS AND SPLITTING SAID FLOW INTO A MULTITUDE OF SMALL STREAMS,AND DIRECTING THE FLOW OF SAID MULTITUDE OF SMALL LIQUID STREAMS INTO ACONTAINER AT ATMOSPHERIC